Let’s suppose that the hydraulic system gets in trouble due to a defective pump, damaged pipe or the like and that the steering resistance is too high to use the power steering system. In such case, the steering wheel can be in the manual mode. When the steering wheel is turned, the torsion bar is twisted for the valve’s stroke and from now on the steering wheel functions in the manual mode. It should be noted that the steering wheel’s play becomes larger than that in the power steering mode.